Research in Atmospheric Chemistry (Rudolph’s Group)

Isotope ratio measurements of atmospheric organic compounds:
An emerging promising tool to gain new insight into the
atmospheric chemistry of volatile organic compounds

Volatile organic compounds (VOC) play a key role in the chemistry of the atmosphere. They contribute significantly to the formation of secondary pollutants such as ozone and particulate organic matter and also influence the concentration of OH-radicals in the atmosphere, which determines the atmospheric residence time of many important pollutants. During the last decades numerous studies of the sources, reactions, and
distributions of atmospheric VOC have been made. However, in spite of the substantial progress and the large number of studies, there are still substantial gaps in the understanding of atmospheric VOC chemistry.In 1997 Rudolph et al (GRL, 1997 #65) published a paper which described a methodology for compound specific measurements of the stable carbon isotope ratios of atmospheric VOC. Isotope ratio measurements have been extremely valuable for gaining insight into important atmospheric trace gases such as carbon dioxide, carbon monoxide, methane and nitrous oxide. The availability of a method for VOC isotope measurements opened the possibility to use stable isotope ratio information for studies of the
Atmospheric Chemistry of VOC. However, the interpretation of VOC isotope ratio measurements requires knowledge of the isotopic composition of VOC emissions and the kinetic isotope effects for atmospheric reactions of VOC as well as concepts for the interpretation of the isotope data.Since more than 10 years the main emphasis of our research was to create the necessary knowledge and data, which would allow develop the framework and methodology which is necessary to interpret VOC isotope ratio studies.